In the latest episode of the reality TV show, the 51-year-old was with the former Ukip leader for less than 48 hours in camp before he questioned his motivation for wanting the UK to leave the European Union in 2016.
Sirieix said the average person had "lost out" now that Britain is no longer part of the EU, but Mr Farage insisted "they haven't lost out".
He described Mr Johnson as "one of the most disorganised human beings that possibly ever lived".
Ms Gibson asked what Mr Johnson was personally like, to which Mr Farage said: "Entertaining in small doses. (He’s) surprisingly introverted.
"You see this big act, fluffing the hair… surprising."
Questioned on if the former prime minister was "a fumbler in real life", he added: "I think he’s one of the most disorganised human beings that possibly ever lived.
"The whole thing’s bloody chaos. Shambles."
Mr Siriei then asked Mr Farage: "What’s the benefit of Brexit then? If you are an average person from Britain, what’s the benefit?"
The GB News presenter replied: "To know that we’re independent, we stand on our own two feet in the world."
Mr Siriei shot back: "Brexit was about immigration, I remember your poster. I thought it was shameful what you did Nigel. Shameful."
Mr Farage replied: "Sadly, sadly it was absolutely true. It was a poster showing mass young men moving illegally across borders."
He then denied that the anti-EU poster in 2016, which showed a long queue of migrants, was about "demonising migrants".
Mr Sirieix said: "I think the average person in the UK has lost out because of what you’ve done." Mr Farage said: "They haven’t lost out."
In the Bush Telegraph Mr Farage said: "I knew it wouldn’t take long, I knew politics would rear its head as indeed it did. And Fred feels very strongly about it.”
Mr Sirieix said afterwards: "Look, Nigel Farage is in the jungle with me. We’re bound to have this conversation. At the end of the day nothing is going to change, Nigel believes what he believes, I believe what I believe."
Mr Farage then tucked into a pizza topped with four different animal penises as he took on his first bushtucker trial.
He teamed up with YouTuber Nella Rose for the Jungle Pizzeria task, with the pair winning nine of ten stars for their efforts.
Among the various other unappetising toppings Mr Farage chowed down on included camel and sheep udder, cow and goat feet and blended bull’s tongue.
As Ms Rose tried not to vomit while tasting dishes that included giant mealworms and fly pupae, Mr Farage offered her words of encouragement.
For his last meal, Mr Farage had to eat a slice with a sheep, pig, bull and crocodile penis – which secured him his fifth and final gold star.